To put our fits in perspective we compare WZDR+ to two other models: \(\Lambda \) CDM and SIDR+, a model in which self-interacting dark radiation (SIDR) weakly interacts with the DM [1]}, [2]}. SIDR+ is a natural model to compare to because it also has i. extra radiation which is important for the Hubble tension and ii. friction between dark radiation and dark matter which is important to address the \(S_8\)  tension; relative to WZDR+ it is just missing the mass threshold, the “step”.
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